I think the orig sight has been pushed back due to the gun being dropped or otherwise struck on the F/Sight.
The blued finish of the bbl all looks factory including the polished over 2 pins holding the ramp on.
If those had been messed with in an aftermarket install, they'd show that. Not the perfect polish and blue that they do.
I don't think it's a cut bbl (with a bad sight re-install). The bbl lettering would be off if it was a 6 down to a 4.
The web that the pins go thru is stout but the pins can shear with enough force if applied to the sight/ramp. The tight fit of the pins betw the ramp and the web do actually act as a 'shears' in cutting action.
The web on the ramp can break though where the pin holes are drilled if there isn't much material betw the hole and the outside edge.
You can test to see if the ramp is sheared off the pins or the web broken through easily enough.
Put the bbl in a padded vise holding it horizontaly.
Take a wooden dowel or a rawhide mallet and tap on the ramp/sight blade from the breech end (back end) and see it it can be pushed back into position,,,,down and forward.
If it can, then the pins are sheared off inside and the tight fit of the ramp web & interference from those sheared off pins is all that's holding it onto the bbl.
You might loose the front sight completely firing some stout ammo if that is the case.
Better to find out before that and re-attach it securely.
If that is NOT the case and it's just a bad factory sight install (the era wasn't the best QC S&W was ever known for),,then decide wether you want to live with it as is, or go for a cosmetic fix up.
JMO